By Lee Joon-seung SEOUL, Sept. 19 (Yonhap) -- Ahn Cheol-soo's long awaited announcement to run for president has effectively heralded the start of a three-way race to pick the country's next chief executive, and will spur talks to pick a single opposition candidate ahead of the December election, political observers said Wednesday.

The decision by the founder of Ahnlab, the country's largest anti-virus software company, and dean of a convergence science graduate school at Seoul National University, will pit Ahn against the ruling Saenuri Party's presidential hopeful Park Geun-hye, and the main opposition Democratic United Party's (DUP) candidate Moon Jae-in.

Most observers said Ahn's announcement to formally compete for the country's top elected office was no surprise since he has come too far to turn back.

"It would have been a real surprise if he decided not to run in the presidential race after all this time," a senior pollster at a survey firm said.

The 50-year-old dean came into the political spotlight when he played an instrumental role in getting relatively obscure civic leader Park Won-soon elected as Seoul mayor in last year's by-election. Ahn has since criticized the ruling party and the incumbent Lee Myung-bak administration for bad management of the country and called for overall political change. This has made him a contender for the opposition camp.

Despite not formally announcing his intention to run for public office until Wednesday, Ahn has been running neck-and-neck with Saenuri's Park in polls to assess the person most fit to run the country. He is particularly popular among young people and urban dwellers.

Rep. Song Ho-chang, a lawmaker from the DUP with close ties to Ahn, said for the time being, the entrepreneur-turned-politician will have to take active steps to gain recognition from the public on his ability to run the country and win trust.

One of Ahn's greatest weaknesses is that he has never held any public office, although this in the past has helped boost his "clean" image. Many South Koreans do not think highly of their politicians.

Cho Dong-keun, a social economics professor at Myongji University in Seoul, said Ahn will now have to shed his reliance on "image" to win favor and start to show the people what he will do if he is elected.

The professor said while the public does not expect politicians to be morally perfect, they do think they must be honest and have integrity.

"In this respect, there is a need to check the validity of what he said in past lectures, TV appearances and books with his actual life," Cho said.

Ahn in recent months had to fend off criticism that his actions have not corresponded with his words. In one instance, the dean was not able to clearly explain how he became the owner of a small apartment when he was still a graduate student with no money.

He also had to fend off allegations of irregularities in the issuing of corporate bonds and claims of bribe-giving during the time of AhnLab's growth period.

Besides trying to explain himself to the public, Ahn will have to engage in negotiations with Moon over the need for a single candidate to represent the opposition in the Dec. 19 poll.

This move, more than anything, will be critical in how this year's presidential election unfolds.

All domestic polls taken have indicated that a three-way race will hand the presidency to Park. If there is a one-on-one race, between Park and an opposition candidate, surveys place the odds more evenly.

Park is the daughter of late President Park Chung-hee, and because of this connection, she enjoys strong support among the country's conservatives and the older generation.

The late president is widely credited with South Korea's rapid economic growth, which was achieved at the cost of the harsh suppression of any form of political dissent. Surveys differ but the latest poll conducted by RealMeter and a cable TV channel on 1,500 people nationwide, showed Moon's approval rating hitting 47.1 percent, higher than the 44.0 percent for Park. The same findings showed Park ahead of Ahn at 44.7 percent to 44.5 percent.

Moon Jae-in (L), Ahn Cheol-soo (Yonhap file photo)

The survey firm said Moon's higher number is the first since it started conducting such polls.

In addition, starting from last week, Moon has started to gain an advantage over Ahn in a hypothetical race to pick a single opposition candidate, with the RealMeter poll giving Moon a substantial 44.9 percent to 32.3 percent advantage over Ahn.

"The latest developments are partly due to the so-called convention effect generated by Moon's victory in the DUP's primary on Sunday, but it is a sign that public views towards Moon may be changing," a survey analyst said.

Many political observers, meanwhile, predicted the DUP candidate and Ahn will join hands in the end because there is no alternative for the DUP or Ahn.

"For the time being Moon and Ahn need to increase their public exposure and each try to win the trust of the people by highlighting what they will do if they take power," said Lee Cheol-hee, director of Dumun Political Strategy Institute.

He said by engaging in constructive debate and competing fairly to win the support of voters, Moon and Ahn can create a positive synergy effect. Lee said only after this stage of building support should the two try to iron out a deal for a single candidate.

This should take place before late November, when candidates must formally register with election authorities if they want to run for office.

This view was echoed by Lee Nae-young, a political science professor at Korea University and Korea Society Opinion Institute chief analyst Yoon Hee-woong, who claimed the opposition will settle on a single candidate in the end.

"The DUP seems to hope that Ahn will again concede his candidacy as he did last year ahead of the Seoul mayoral election," Lee said.

Others, however, were more pessimistic and predicted it may not be easy for the two men to reach an understanding because supporters of Moon and Ahn do not completely overlap.

Shin Yul, a political science professor at Myongji University, said it will be effectively hard for the DUP not to send a candidate in December, while Ahn may be pressured to retain his separate identity because his main support base is centered on people opposed to the present political landscape and wanting change.

"Ahn will probably not want to be associated with the DUP unless Park takes a commanding lead in the polls in the coming three months," the political analyst said.

Related to how public opinion will move in the coming months, domestic survey companies said if Ahn decides to step down and concede the candidacy to Moon, there may be some defection among his supporters, while there may be less if the DUP candidate opts not to run.

"Many of Ahn's supporters are politically neutral or don't like parties outright, so if the dean does not run, these people will either not vote or could even turn to the Saenuri candidate if she is able to upgrade her image," a pollster said. He said, however, that because Moon's supporters are on the whole anti-Park and oppose the ruling party, they will vote for anyone they think will serve their purpose.

There will be many fluctuations in opinions, but if the race remains very close, voters wanting a change in power will pick the candidate with the best chance of beating Park, analysts said.